Radiation meter and method

ABSTRACT

The present invention relates to a method and radiation monitoring device ( 10 ) comprising at least one radiation detector ( 111 ), a memory ( 112 ) and a controller ( 12 ), wherein said radiation detector is arranged to detect at least one type of radiation dose. The memory ( 112 ) comprises a number of memory positions configured to store data resulting from said detector ( 111 ) detection. The positions are configured to store accumulated measured dose values corresponding to consecutive real time intervals. The controller is configured to continuously compute mean radiation dose values for measured and stored radiation doses during the predetermined time period and for each computation, a resulting mean value is compared with a corresponding predetermined reference value and generate a signal corresponding to result of said comparison.

TECHNICAL FIELD

The present invention relates to monitors for radiation, and inparticular to radiation dose meters.

BACKGROUND

Human tissue is sensitive for different types of radiation. Theradiation which may consist of energy bins may affect cell structureswhen it hits the human body. Ionizing radiation, for example, can changethe structure of the cells, sometimes creating potentially harmfuleffects that are more likely to cause changes in tissue. These changescan interfere with cellular processes so cells might not be able todivide or they might divide too much, resulting in cancer.

Radiation dose meters are common for use in industries, hospitals,dentist sites, etc. in which the presence of and exposure to low levelsof radiation is a hazard and must be monitored. In a hospital or atdentist, for example, patients, physicians and nurses may also encountersituations in which they may risk exposure to radiation and require ameans of monitoring such exposure.

The radiation dose meters of today normally provide a direct value in apredetermined unit. However, to present measured values in this waynormally is not easy to be understood by none-expert users and to beinterpret to a relevant radiation dose situation and consequentlyunclear for the user how to avoid unnecessary exposure to radiation,which may increase health hazard.

Authorities have specified some radiation dose limits, which should notbe exceeded for individuals/groups of people, to reasonably limithumans' health risks for radiation.

U.S. Pat. No. 4,642,463 relates to a radiation monitor, which includes aradiation detector, a digital processor and a display. The digitalprocessor is responsive to externally input information corresponding toalarm radiation rate, alarm radiation dose and alarm time-to-go. Thedigital processor integrates the perceived real time radiation rate toproduce total dose information. The processor can then compare totaldose information to alarm dose, compare sensed radiation rates to alarmrate and compute time-to-go, by dividing the difference between alarmdose and total dose by the present radiation rate, and finally comparingcomputed time-to-go to alarm time to go. The processor initiates analarm condition for altering the user of sensed radiation rate exceedsalarm radiation rate, if total dose information exceeds alarm doseinformation or if time-to-go, as computed, is less than alarm time-to-goinformation. Additional functions performed include determination ofexpected dose, first opportunity computations and decay time-to-gocomputations. In all these computations the processor is capable ofextrapolating predicted radiation rates. Thus, this document describes atechnique using accumulated dose while the present invention usescontinues running mean value and radiation intensity. There is also adifference in when and how a warning is provided. While the presentinvention provides a warning for whether the radiation at the currenttime is safe or not, this document provides information on how long itis left before the radiation is unsafe.

U.S. Pat. No. 7,592,603 relates to a radiation detector performing bothrate and dose measurements for personal safety and also to providemeasurements that are sufficiently sensitive for security applications.In one embodiment, a radiation detector has a first measurement channeland a second measurement channel, where the second measurement channelcan measure radiation at levels that would saturate the firstmeasurement channel.

SUMMARY OF THE INVENTION

One of the objects of the present invention is to provide an arrangementfor measuring and providing measurement value, which is easy to beapprehended and indicates that the current radiation dose over apredetermined time interval should be avoided under a longer timeinterval to avoid health risks.

For this reason the present invention relates to a radiation monitoringdevice comprising at least one radiation detector, a memory and acontroller, wherein the radiation detector is arranged to detect atleast one type of radiation dose. The memory comprises a number ofmemory positions configured to store data resulting from the detectordetection. The positions are configured to store accumulated measureddose values corresponding to consecutive real time intervals. Thecontroller is configured to continuously compute mean radiation dosevalues for measured and stored radiation doses during the predeterminedtime period and for each computation, a resulting mean value is comparedwith a corresponding predetermined reference value and generate a signalcorresponding to the comparison. The device may further comprise adisplay unit. Depending on one or several current mean values exceedingor being below a corresponding reference value for a chosen timeinterval, the controller is configured to generate a control signal fordisplaying a specific symbol on the display. The time interval is one orseveral of second, minute, hours, day, week, month or year. The memoryunit comprises a number of memory cells, each cell for storing aradiation dose data within a predetermined time interval, whereincell_(n) is configured to store a radiation dose under a time interval nand cell_(n+1) stores radiation dose in a subsequent real time interval.A total number of cells correspond to a relevant larger time intervalthan a largest chosen measuring time interval n. The device may beconfigured to control one or several indicators to indicate a firstsymbol apprehended as safe radiation dose exposure and one or severalsecond symbols apprehended as unsafe radiation dose exposure. Theradiation dose is a functional of dose intensity as a function of a timeperiod −a to t:

Radiation  dose = ∫_(−a)^(t)dose  intensity  t

The device may be intended for monitoring different type of radiationscomprising ionized radiation, being one or several of alpha particles,beta particles, gamma rays, X-ray radiation, and neutrons, andnon-ionized radiations, being one of several of radio waves, light (UVand IR) or a combination of radiations. The device may comprise meansfor detecting the position on which the device is installed.

The invention also relates to a method of monitoring radiation by meansof a radiation monitoring device comprising at least one radiationdetector, a memory and a controller. The radiation detector is arrangedto detect at least one type of radiation dose. The memory comprises anumber of memory positions configured to store data resulting from thedetector detection. The method comprising: storing in the positionsaccumulated measured dose values corresponding to consecutive real timeintervals, continuously computing mean radiation dose values formeasured and stored radiation doses during the predetermined time periodand for each computation, and comparing a resulting mean value with acorresponding predetermined reference value and generate a signalcorresponding to the comparison.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention is described with references toexemplary embodiments illustrated in the attached drawings, in which:

FIG. 1 is a schematic block diagram of a radiation dose measuring deviceaccording to the present invention,

FIG. 2 is an exemplary graph illustrating the relationship between doseintensity and time period for reference dose values and

FIG. 3 illustrates exemplary method steps of the invention.

DETAILED DESCRIPTION

FIG. 1 is a schematic block diagram of a radiation dose measuring device10 according to the present invention. The device comprises a measuringpart 11, a controller 12, and a display unit 13. Power source and otherunits not relevant for the invention are not illustrated.

The measuring part 11 comprises a detector 111 and a memory unit 112.The measuring part 11 may also comprise (in addition to or instead ofdetector 111) an input 113 for receiving measured dose. One or severaltypes of detectors may be incorporated.

The memory unit 112 may comprise a number of memory cells, each cell forstoring a radiation dose data within a predetermined time interval. Thetime interval may be a time unit, such as second, minute, hour, day,week, etc. The memory cell structure is configured such that cell_(n)stores the radiation dose under time interval n and cell_(n+1) storesradiation dose in the subsequent real time interval, and so on.Preferably, the total number of cells should correspond to a relevantmuch larger time interval than the largest chosen measuring timeinterval n, e.g. months or years.

The memory unit 112 may be part of the main memory of the device.

The controller 12 is configured to execute instructions (e.g. stored ina memory not shown). The instructions may comprise instruction set forcontrolling the measuring unit 11, the display unit 13 and otherinternal functionalities. The instructions also comprise a number ofcomputational instructions which continuously compute (current) meanvalues for the radiation dose during the predetermined time period (e.g.second, minute, hour, day, week, etc.). For each new computation, theresulting mean value is compared with predetermined reference values. Ifone or several current mean values exceed corresponding reference valuefor chosen time interval, a control signal is generated to the displayunit 13.

The reference values and time periods may be pre-programmed for specificapplications or changed for different applications.

FIG. 2 is an exemplary graph illustrating the relationship betweenreference doses and time period.

According to graph of FIG. 2 following relations may be valid:

Radiation dose A<Radiation dose B<Radiation dose C

|a|<|b|<|c|

Wherein:

Radiation  dose  A = ∫_(−a)^(now)dose  intensity  tRadiation  dose  B = ∫_(−b)^(now)dose  intensity  tRadiation  dose  C = ∫_(−c)^(now)dose  intensity  t

For example, radiation dose A may be 100 μSv, radiation dose B may be200 μSv and radiation dose C may be 300 μSv.

When computing, the controller compares radiation dose A with the realradiation dose for the time interval a. If the radiation dose>radiationdose A (reference value according to FIG. 2) a signal is transmitted tothe display unit. Same computation and comparisons are made to for thetime intervals b and c to radiation doses B and C, respectively

The display unit 13 comprises, for example a Liquid Crystal Display(LCD) portion 131 (or any other suitable display technique), which maybe controlled by the controller 12 or a display driver (not shown), wellknown for a skilled person. The display portion may be colour display or“black and white”. The display unit may also be provided with anidentification field 132, identifying the user, i.e. a person or asubject carrying the radiation dose monitoring device 10.

The display unit 13 is configured to provide information to a user in asimple but accurate manner. For this reason the display portion 131 maydisplay a number of symbols reproducing the detected radiation dose. Forexample, a first symbol 133 may only indicate that the radiation dose iswithin an acceptable limit by only displaying “OK”. One or severalsymbols 134 may be used to provided information for a time intervalduring which current radiation dose is compared to respective referenceradiation dose. The display portion may also provide information 135about the position on the user the radiation dose monitoring device iscarried.

The position in which the device is carried, is important because theamount of radiation varies depending on, e.g. if the user carriesadditional protection, field of use etc., and thus the reference valuesdepend on the position.

During the monitoring operation, if none of the current mean values ofthe measured radiation doses exceed respective reference value, theacceptable limit symbol (“OK”) is displayed. If the current radiationdose A exceeds reference radiation dose A, a corresponding symbol (134)may be displayed. This symbol may for example be “Warning”, red colouredsymbol (or any other warning symbol) or combinations thereof. Thissymbol may be displayed until measured radiation dose mean value duringthe latest measuring interval “a” is below the reference radiation doseA. The acceptable limit symbol is off while the warning symbol isdisplayed. Thus, there is no need for displaying dose level values whichare not understood by non-experts.

If several current radiation doses (A, B, C) exceed the respectivereference dose (A, B, C), a corresponding symbol may be displayed.

In one embodiment, if the user obtains indication (134) corresponding toa warning, the radiation dose intensity as function of time may beanalyzed in more detail. Data in the memory unit 112 can be transferredto a database using wired or wireless communication, for furtheranalyses.

In yet another embodiment, the device doesn't have a display andcontinuously communicate with other information displaying units or acentral computer at a monitoring site.

The device of the invention may be used for monitoring any type ofradiations, e.g. ionized radiation such as alpha particles, betaparticles, gamma rays, X-ray radiation, and neutrons, and non-ionizedradiations, such as radio waves, light (UV and IR) or a combination ofradiations.

In yet another embodiment, the device may be configured to detect theposition it is carried on, e.g. by detecting altitude, ambient material,etc.

It should be noted that the word “comprising” does not exclude thepresence of other elements or steps than those listed and the words “a”or “an” preceding an element do not exclude the presence of a pluralityof such elements. It should further be noted that any reference signs donot limit the scope of the claims, that the invention may be implementedat least in part by means of both hardware and software, and thatseveral “means”, “units” or “devices” may be represented by the sameitem of hardware.

The various embodiments of the present invention described herein isdescribed in the general context of method steps or processes, which maybe implemented in one embodiment by a computer program product, embodiedin a computer-readable medium, including computer-executableinstructions, such as program code, executed by computers in networkedenvironments. A computer-readable medium may include removable andnon-removable storage devices including, but not limited to, Read OnlyMemory (ROM), Random Access Memory (RAM), compact discs (CDs), digitalversatile discs (DVD), etc. Generally, program modules may includeroutines, programs, objects, components, data structures, etc. thatperform particular tasks or implement particular abstract data types.Computer-executable instructions, associated data structures, andprogram modules represent examples of program code for executing stepsof the methods disclosed herein. The particular sequence of suchexecutable instructions or associated data structures representsexamples of corresponding acts for implementing the functions describedin such steps or processes.

Software and web implementations of various embodiments of the presentinvention can be accomplished with standard programming techniques withrule-based logic and other logic to accomplish various databasesearching steps or processes, correlation steps or processes, comparisonsteps or processes and decision steps or processes. It should be notedthat the words “component” and “module,” as used herein and in thefollowing claims, is intended to encompass implementations using one ormore lines of software code, and/or hardware implementations, and/orequipment for receiving manual inputs.

The foregoing description of embodiments of the present invention, havebeen presented for purposes of illustration and description. Theforegoing description is not intended to be exhaustive or to limitembodiments of the present invention to the precise form disclosed, andmodifications and variations are possible in light of the aboveteachings or may be acquired from practice of various embodiments of thepresent invention. The embodiments discussed herein were chosen anddescribed in order to explain the principles and the nature of variousembodiments of the present invention and its practical application toenable one skilled in the art to utilize the present invention invarious embodiments and with various modifications as are suited to theparticular use contemplated. The features of the embodiments describedherein may be combined in all possible combinations of methods,apparatus, modules, systems, and computer program products.

1. A radiation monitoring device configured to generate a signalnotifying for further exposure to a radiation dose with respect to acurrent radiation dose over a predetermined time interval andcomprising: at least one radiation detector arranged to detect at leastone type of radiation dose intensity, a memory comprising a number ofmemory positions configured to store data resulting from said at leastone radiation detector detection, said positions being configured tostore accumulated measured dose values corresponding to consecutive realtime intervals, and a controller configured to continuously compute andgenerate mean radiation dose intensity values for measured and storedradiation doses during a predetermined time period and for eachcomputation, compare a resulting mean value is with a correspondingpredetermined reference value and generate a signal corresponding toresult of said comparison, said resulting signal indicating at least alevel to a specific radiation dose intensity at a specific time.
 2. Theradiation monitoring device of claim 1, further comprising a displayunit.
 3. The radiation monitoring device of claim 2, wherein thecontroller is configured to generate a control signal for displaying aspecific symbol on said display depending on one or several current meanvalues exceeding or being below a corresponding reference value for achosen time interval.
 4. The radiation monitoring device of claim 1,wherein said time interval is one or several of second, minute, hour,day, week, month or year.
 5. The radiation monitoring device of claim 1,wherein said memory comprises a number of memory cells, each cellconfigured for storing a radiation dose data within a predetermined timeinterval, such that cell_(n) is configured to store a radiation doseunder a time interval n and cell_(n+1) stores radiation dose in asubsequent real time interval.
 6. The radiation monitoring device ofclaim 5, wherein a total number of cells corresponds to a relevantlarger time interval than a largest chosen measuring time interval n. 7.The radiation monitoring device of claim 2, comprising one or severalindicators configured to indicate a first symbol apprehended as saferadiation dose exposure and one or several second symbols apprehended asunsafe radiation dose exposure.
 8. The radiation monitoring device ofclaim 1, wherein said radiation dose intensity is a function of a timeperiod −a to t: Radiation dose=∫_(−a) ^(t) dose intensity dt wherein tis current time.
 9. The radiation monitoring device of claim 1,comprising one or several detectors for monitoring different type ofradiations comprising: one or several of: ionized radiation, being oneor several of alpha particles, beta particles, gamma rays, X-rayradiation, and neutrons, and non-ionized radiations, being one ofseveral of radio waves, light (UV and IR) or a combination ofradiations.
 10. The radiation monitoring device of claim 1, comprisingmeans for detecting the position on which the radiation monitoringdevice is installed.
 11. A method of monitoring radiation by means of aradiation monitoring device including: at least one radiation detectorarranged to detect at least one type of radiation dose intensity, amemory including a number of memory positions configured to store dataresulting from said at least one radiation detector detection, andcontroller, the method comprising: continuously storing in said memorypositions accumulated measured intensity of dose values corresponding toconsecutive real time intervals, continuously computing mean radiationdose values for measured and stored radiation doses during thepredetermined time period and for each computation, continuouslycomparing a resulting mean intensity value with a correspondingpredetermined reference value, and generating a signal, which notifiesfor further exposure to a radiation dose with respect to a currentradiation does over a predetermined time interval.
 12. The method ofclaim 11, wherein based on result of said comparison: generating a firstsymbol comprehended as a first radiation dose level intensity, orgenerating a second symbol comprehended as a second radiation dose levelintensity.
 13. A radiation monitoring device configured to generate asignal notifying for further exposure to a radiation dose with respectto a current radiation dose over a predetermined time interval andcomprising: at least one radiation detector arranged to detect at leastone type of radiation dose intensity, a memory comprising a number ofmemory positions configured to store data resulting from said at leastone radiation detector detection, said positions being configured tostore accumulated measured dose values corresponding to consecutive realtime intervals, a controller configured to continuously compute andgenerate mean radiation dose intensity values for measured and storedradiation doses during a predetermined time period and for eachcomputation, compare a resulting continuous mean value with acorresponding predetermined reference value and generate a signalcorresponding to result of said comparison, said resulting signalindicating at least a level to a specific radiation dose intensity at aspecific time, and a display comprising a viewing field for displayingan image with respect to said resulting signal, wherein the display isconfigured to, if none of current mean values of the measured radiationdoses exceed respective reference value, a symbol for acceptable doselimit is displayed and if the current radiation dose exceeds a referenceradiation dose, a corresponding warning symbol is displayed.
 14. Theradiation monitoring device of claim 13, wherein said symbols compriseone or several of characters, colors or images.